When an LDO is activated, an output capacitor of the LDO is charged to a nominal voltage as fast as possible which causes a large amount of current to flow (inrush current). The power source for an LDO, included in a system, can have variable characteristics and constraints. Because of the finite impedance of the sources, these types of LDOs are expected to limit the initial charging current. Large inrush current can cause the power source to dip dangerously low, at times even low enough to cause system-level problems. Many LDOs do not support an inrush current limit feature. Absence of this key feature creates problems that become especially severe if the LDO is capable of high load current, and if an input source is a switching converter. Output of the switching converter can be pulled down by a large inrush current that flows into charge the output capacitor, triggering the switching regulator enable circuit, and in some cases forcing the circuit to reset. The step-down regulator may then cycle between charging and reset states. There needs to be a startup circuit that can limit inrush current in LDOs.